The Common Basis of Intramolecular Rearrangements. II.¹ The Dehydration of Di-tert-butylcarbinol and the Conversion of the Resulting Nonenes to Trimethylethylene and Isobutylene

Isomerization of Hydrocarbons.

“…and the catalyst was palladium, the octenes are undoubtedly sufficiently stable to furnish some very interesting isomerization reactions. However, the work of Whitmore and Stahly (131) on the dehydration of methyl-di-tertiary-butylcarbinol and that of Nasarow (88) on ethylisopropyl-t ertiary-butylcarbinol showed that the higher olefins split and rearrange into smaller olefins in line with the experimental equilibrium data for these olefins. This indicates, as would be expected, that the higher olefins are less stable than the lower olefins and in the presence of a catalyst decompose readily.…”

Thermodynamic behavior of alkanes in superacid media

“…In the superacid media derived from HS03F, the reduction of HS03F by hydrogen is exothermic89 and thus may occur. Furthermore, the oxidation of alkanes in HS03F by S03 has been shown;90*92 S03 is produced by the dissociation of HS03F into HF and S03,33,34,93 the overall oxidation process being RH + 3HS03F -R+ + S03F-+ S02 + 2HF+ H2S04 (7) In the mixtures HS03F + SbF5, SbF5 participates in the oxidation of alkanes94 as was earlier observed in the oxidation of hydrocarbons by SbCl5. 95 In sulfuric acid, it has been established much earlier than the formation of carbenium ions from alkanes proceeds via the reduction of sulfuric acid into S02.…”

“…5 These acid-catalyzed transformations of saturated hydrocarbons (fragmentation, alkylation, isomerization) were generally considered to be carbocation reactions involving trivalent carbenium ions. [6][7][8][9][10] Direct evidence for the existence and structures of alkylcarbenium ions became possible largely through the application of NMR spectroscopy and the use of superacid media.11, 12 The observation of long-lived carbocations has opened a wide field of investigation, first concerning the physicochemical properties of these species and then relative to reactions that can proceed from them. 13"16 In this respect, the catalytic isomerization or alkylation of alkanes, of special interest for the upgrading of motor fuels, may be regarded as one of the most promising applications of superacid media.…”

“…Figure7. Potential-acidity diagrams of pentane in superacid media: n-C5H, n-pentane; i-C6H, isopentane; neo-C5H, neopentane; see Figure6.…”

C‐C‐Fragmentierung: Herkunft und jüngste Anwendungen

“…Die Etablierung dieses Reaktionstyps ist auf Slawjanov63a und Kalishev63b zurückzuführen, die unabhängig voneinander die säureinduzierte Umwandlung von Hexamethyl‐1,3‐propandiol zu Isobutylen und Aceton beschrieben ( 64 → 67 und 68 mit R 1 , R 2 , R 3 =CH 3 ; Schema ). Whitmore und Stahly demonstrierten 1933 einen ähnlichen Prozess bei der Dehydrierung von Di‐ tert ‐butylcarbinol ( 69 ) 64. Der Abspaltung von Wasser und der Bildung eines sekundären Carbokations folgt eine 1,2‐Methylverschiebung und dann eine C‐C‐Fragmentierung unter Erzeugung von Trimethylethylen ( 73 ) und Isobutylen 65…”